DuckDB: test curl impl, don't auto-load extensions

[myrrc]

#6658 but without github action changes

[codspeed-hq]

Merging this PR will improve performance by 43.03%

⚡ 1 improved benchmark
✅ 953 untouched benchmarks
⏩ 1466 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	chunked_bool_canonical_into[(1000, 10)]	68.2 µs	47.7 µs	+43.03%

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_{Comparing myrrc/duckdb-build-from-hash-ci-1 (298cc67) with develop (8a9185a)}

Footnotes

1. 1466 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩